G-SYNC 101: Control Panel

G-SYNC Module

The G-SYNC module is a small chip that replaces the display’s standard internal scaler, and contains enough onboard memory to hold and process a single frame at a time.

The module exploits the vertical blanking interval (the span between the previous and next frame scan) to manipulates the display’s internal timings; performing G2G (gray to gray) overdrive calculations to prevent ghosting, and synchronizing the display’s refresh rate to the GPU’s render rate to eliminate tearing, along with the delayed frame delivery and adjoining stutter caused by traditional syncing methods.

G-SYNC Activation

“Enable for full screen mode” (exclusive fullscreen functionality only) will automatically engage when a supported display is connected to the GPU. If G-SYNC behavior is suspect or non-functioning, untick the “Enable G-SYNC, G-SYNC Compatible” box, apply, re-tick, and apply.

G-SYNC Windowed Mode

“Enable for windowed and full screen mode” allows G-SYNC support for windowed and borderless windowed mode. This option was introduced in a 2015 driver update, and by manipulating the DWM (Desktop Windows Manager) framebuffer, enables G-SYNC’s VRR (variable refresh rate) to synchronize to the focused window’s render rate; unfocused windows remain at the desktop’s fixed refresh rate until focused on.

G-SYNC only functions on one window at a time, and thus any unfocused window that contains moving content will appear to stutter or slow down, a reason why a variety of non-gaming applications (popular web browsers among them) include predefined Nvidia profiles that disable G-SYNC support.

Note: this setting may require a game or system restart after application; the “G-SYNC Indicator” (Nvidia Control Panel > Display > G-SYNC Indicator) can be enabled to verify it is working as intended.

G-SYNC Preferred Refresh Rate

“Highest available” automatically engages when G-SYNC is enabled, and overrides the in-game refresh rate selector (if present), defaulting to the highest supported refresh rate of the display. This is useful for games that don’t include a selector, and ensures the display’s native refresh rate is utilized.

“Application-controlled” adheres to the desktop’s current refresh rate, or defers control to games that contain a refresh rate selector.

Note:this setting only applies to games being run in exclusive fullscreen mode. For games being run in borderless or windowed mode, the desktop dictates the refresh rate.

G-SYNC & V-SYNC

G-SYNC (GPU Synchronization) works on the same principle as double buffer V-SYNC; buffer A begins to render frame A, and upon completion, scans it to the display. Meanwhile, as buffer A finishes scanning its first frame, buffer B begins to render frame B, and upon completion, scans it to the display, repeat.

The primary difference between G-SYNC and V-SYNC is the method in which rendered frames are synchronized. With V-SYNC, the GPU’s render rate is synchronized to the fixed refresh rate of the display. With G-SYNC, the display’s VRR (variable refresh rate) is synchronized to the GPU’s render rate.

Upon its release, G-SYNC’s ability to fall back on fixed refresh rate V-SYNC behavior when exceeding the maximum refresh rate of the display was built-in and non-optional. A 2015 driver update later exposed the option.

This update led to recurring confusion, creating a misconception that G-SYNC and V-SYNC are entirely separate options. However, with G-SYNC enabled, the “Vertical sync” option in the control panel no longer acts as V-SYNC, and actually dictates whether, one, the G-SYNC module compensates for frametime variances output by the system (which prevents tearing at all times. G-SYNC + V-SYNC “Off” disables this behavior; see G-SYNC 101: Range), and two, whether G-SYNC falls back on fixed refresh rate V-SYNC behavior; if V-SYNC is “On,” G-SYNC will revert to V-SYNC behavior above its range, if V-SYNC is “Off,” G-SYNC will disable above its range, and tearing will begin display wide.

Within its range, G-SYNC is the only syncing method active, no matter the V-SYNC “On” or “Off” setting.

Currently, when G-SYNC is enabled, the control panel’s “Vertical sync” entry is automatically engaged to “Use the 3D application setting,” which defers V-SYNC fallback behavior and frametime compensation control to the in-game V-SYNC option. This can be manually overridden by changing the “Vertical sync” entry in the control panel to “Off,”“On,” or “Fast.”

I’m having a really weird issue that I’m not sure is a driver or monitor problem. Whenever my fps is below Half Refresh (72 for 144Hz) it seems LFC triggers and my refresh rate doubles, 60FPS gives me 120Hz on the Monitor OSD. Is this normal for Gsync or is something messed up here?

Edit: To clarify im well within the freesync range of 48-144 for the monitor while this occurs

Depends. Are you using a FreeSync monitor and Nvidia GPU with the new G-SYNC for FreeSync feature?

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4 months 4 days ago

Member

rybb77

Yeah I’m using it with Gsync. I wish I had an AMD card to test it, it’s the XF240H, they validated the XFA240H and the only difference between the 2 that I know of is one allows for Freesync over HDMI which the driver doesn’t support anyway.

Honestly, I don’t know and can’t say until it has been more thoroughly tested, and where my test results are all relatively replicable across setups due to G-SYNC monitors all having identical/near identical modules and functionality, there are so many FreeSync monitors (both officially supported and unsupported by Nvidia) that vary in specs (including LFC support), I’m not sure how such tests will ever fully be accomplished, since this new G-SYNC on FreeSync functionality relies entirely on (possibly ever changing) driver software, which may interact a little (or a lot) differently with each monitor in combination with each PC setup.

What I can say, is that the LFC behavior you are seeing, at least at the monitor’s OSD-level, does not occur on a G-SYNC monitor with an Nvidia GPU.

My article applies to certified G-SYNC monitors containing a hardware module being run with an Nvidia GPU, and to a lesser degree (at least where the base optimal settings are concerned; those being an -x FPS limit, and the V-SYNC option on for 100% tear-free VRR operation), FreeSync monitors being run with an AMD GPU.

This new G-SYNC on FreeSync feature for Nvidia GPUs on FreeSync monitors is at the driver-level, and software-only, so, at this point, who knows how much it differs from either a standalone G-SYNC or FreeSync setup. Uncharted territory, really.

That’s about all I can offer at this point until more is learned, tested, and/or revealed about this specific version of G-SYNC.

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4 months 4 days ago

Member

rybb77

The weirdest part is that if I alt tab and tab back in the OSD will show 60Hz just starring at the pendulum in the Gsync test. It will stay hoping between 60 and 61 until I move the camera and show the pillar. After that it will jump to 120 and not recover to 60 unless I alt tab again.

Really strange behavior. This is what leads me to believe the driver is a problem, hopefully an update will fix it. Sorry for going sort off topic on your post. Really appreciate the information and testing you guys do.

No need to apologize; the driver feature is advertised as “G-SYNC,” and this is a G-SYNC test article (one of the few around, at that), so it’s still within subject, and a comment discussion I can reference to others that ask about this new driver feature on FreeSync displays, at least until more is known about this specific implementation of G-SYNC.

As for your issue, not all VRR monitors have built-in refresh rate meters, but even the G-SYNC monitors that do (like my own XB271HU) can have read errors (with a 141 FPS limit, my meter spikes from 141 to 144 periodically, even though my tests shows it stays within range regardless of what the meter shows sometimes).

So if you’re not seeing/feeling any ill effects besides what the meter says, my guess is it’s just a readout glitch between the monitor and current driver.

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4 months 4 days ago

Member

bjdr11

Hello! I just registered in blurbusters specifically just to ask this. But I’m an avid reader and fan. Does this settings apply to the newly released “G-Sync Compatible” monitors? Will you test those monitors as compared to the original G-Sync with the original module? That would be really interesting! 😁 Thank you and more power!!!

Regarding standalone FreeSync on a FreeSync-compatible display paired with an AMD GPU, yes, my optimal G-SYNC settings (-3 FPS with the equivalent V-SYNC option “On” for a 100% tear-free experience) should still apply.

As for the driver-level G-SYNC functionality on FreeSync displays, seeing as it is so new, it’s difficult to answer that with 100% certainty…

However, from what I can gather via user reports across the web thus far, and being unable to directly test it myself, the feature appears to be experiencing some teething issues:

1. The V-SYNC option doesn’t appear to be working as a frametime compensation mechanism to 100% prevent tearing during frametime variances in the upper and lower range, and simply reverts to V-SYNC behavior when falling out of the VRR (variable refresh rate) range. 2. The minimum refresh range (aka LFC: low framerate compensation) appears to be currently limited in functionality on the 12 odd FreeSync monitors that Nvidia officially supports, and not functioning at all on unsupported monitors, which means when the framerate drops below the supported physical minimum refresh rate of the given Freesync panel, no refresh duplication behavior occurs to compensate, and it instead reverts either to full V-SYNC behavior (V-SYNC option on) or tearing (V-SYNC option off). 3. There are some reports that -3 FPS isn’t currently enough to always stay in the VRR range with this driver feature, as there appears to be a slower communication rate between the driver and the GPU when directly compared to a genuine G-SYNC module. What that required number is, is unknown until high speed tests are done.

Since the V-SYNC option doesn’t appear to be working (as it does on a genuine G-SYNC module) with the new “G-SYNC on FreeSync” feature, my current recommendation for those that have an Nvidia GPU paired with a FreeSync monitor is to use G-SYNC + V-SYNC “Off” (both in-game and in the NVCP) and limit the FPS to 120 on a 144Hz monitor, for instance.

This should reduce or remove the tearing seen in the upper FPS range near the bottom of the screen by giving enough “breathing room” for frametime variances. However, tearing will still be seen occasionally during frametime spikes, and/or whenever the framerate exceeds or drops below the Freesync monitor’s VRR range.

For lower or higher refresh rates, the number required to reduce tearing in this area may be different, and should be lowered gradually until it diminishes or disappears.

To be extremely clear here, this is currently ONLY necessary for the G-SYNC feature on FreeSync displays, and ONLY because the V-SYNC option doesn’t appear to be working (as it does on a genuine G-SYNC monitor) when paired with this driver-only version of G-SYNC.

As for testing this feature, the Chief Blur Buster does have a FreeSync monitor and an Nvidia GPU, and he has express in the forums that he may be doing some basic high speed tests over the coming months.

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4 months 4 days ago

Member

bjdr11

Thank you for the very thorough reply! As for myself alone, using my naked unprofessional eye, I can not seem to notice any tearing near the bottom of the screen using GSYNC + VSYNC ON (NVCP) + 144FPS CAP. Later I will try G-SYNC + V-SYNC OFF + 120FPS CAP. Thank you for your recommendations and explanations, I am looking forward to your testing or review of the new gsync on freesync feature; and if I may make a request, can you guys include Viewsonic XG2401 in your testing, because that is what I am using right now. Haha! Thank you!

If you’re using G-SYNC + V-SYNC “On” with your FreeSync monitor, there won’t be any tearing at any framerate, but in that scenario, I recommend at least a -3 FPS cap (e.g. 141 FPS) to stay within the VRR range, because if you’re sustaining 144 FPS and have a 144 FPS cap with VRR, you’re basically getting V-SYNC level input lag, which is what the -3 FPS framerate limit is for: to stay within the G-SYNC range.

The G-SYNC + V-SYNC “Off” + 120 FPS scenario is only for users that can’t use the G-SYNC on FreeSync feature without experiencing issues with G-SYNC + V-SYNC “On.”

If you’re not experiencing any of those issues, then keep using G-SYNC + V-SYNC “On” + 141 FPS limit.

Your monitor model isn’t currently on Nvidia’s officially supported list for the new G-SYNC on FreeSync feature, so it goes to show that there is going to be varied and/or a lot of unexpected behavior (either good or bad) depending on the FreeSync monitor model, of which there are many.

I did find an ongoing reddit thread documenting G-SYNC on FreeSync functionality for a variety of FreeSync monitors…

Personally I’m not seeing any issue using G-SYNC + V-SYNC “On” + 141 FPS limit. I think I will continue on using this set up. Thank you for all the helpful links , information and comments! I really appreciate it! More power dude!

I know I am a little late to the party, but I would like to ask something. I find it a little sad that G-Sync just as V-Sync allows for excessive frames to stack up. I have a powerful GPU and so I am (luckily) very often at the top limit of my monitor’s G-Sync range. I feel that I should disable V-Sync with G-Sync and accept some minor tearing for getting the best performance, particularly as I have an IPS display which I love color-wise but which already is far more laggy than my previous 1 ms G-Sync display (TN panel). I would rather not accept the 1 additional frame added by RTSS.

Here comes the question: does the NVCP option “Max. pre-rendered frames” not work? Or not all of the time with all of the games? Should it not do exactly what we all want: disable frame stacking and remove the need for a frame limit? I can’t find this setting being mentioned in your article at all.

I would also like to know whether the respective option in Overwatch does work well. If yes, does it not solve this issue at least for this game? You also stated that this option was ON for all your tests. If it works, you couldn’t have observed frame stacking with Overwatch, right?

And finally I would like to ask whether the 1 frame lag introduced by RTSS only applies when near the set threshold, or whether the limiter is active all of the time and the lag also occurs if operating far below the limit.

Thanks for you time!

EDIT: Out of curiosity, excessive frames stacking up would be limited by VRAM size, right?

(After processing your original comment more fully, I’ve decided to scrap my original replies, and answer it with an entirely new reply more directly; I’ll have my previous two comments removed later. That said, if you would like to continue discussing any of this in more depth, I refer you to the forum: https://forums.blurbusters.com/)

First off, you’re IPS doesn’t necessarily have more input lag than your TN; in fact, it could be the same in that respect, or have even less. What the IPS does have is more motion blur. The 1ms number advertised by your TN is what is called GtG (gray-to-gray), which measures how fast pixels on the display transition from black to white and back. The lower the number, the lower the motion blur.

With that bit out of the way, in part 11 of my article, I never said RTSS added 1 frame of lag over an uncapped framerate within the G-SYNC range. If you go back and read it carefully, I only said RTSS had 1 more frame of lag over an in-game limiter. And as I’ve clarified in the comments section here multiple times before, RTSS can actually have less input lag than uncapped at the same framerate, even within the G-SYNC range (more on this further down).

As for NVCP’s Maximum pre-rendered frames setting, I do have a paragraph on that in part 14 of my article (under “Maximum Pre-rendered Frames: Depends”), and, to be clear here, the pre-rendered frames queue has nothing to do with the need to limit the framerate 3 FPS below the given max refresh rate with G-SYNC enabled. As I stated in a comment a few below yours (when sorted by “NEWEST”): “You need the FPS limit because G-SYNC works by dynamically adjusting the refresh rate, and when the refresh rate is maxed out, it no longer has anything to adjust.”

In simplified terms, unlike the “over-queuing of frames” (which is caused by certain syncing methods’ frame buffers continually overfilling when the framerate is above the max refresh rate, and prevented with an appropriate FPS limit), the Maximum pre-rendered frames setting determines how much “breathing room” the CPU has before it hands frames off to the GPU for display; the larger the queue (say “4”), the less potential there is for frametime spikes (but the higher the input lag), and the smaller the queue (say “1”), the more potential there is for frametime spikes (but the lower the input lag).

The pre-rendered frames queue is typically required to keep frame delivery as uninterrupted as possible, since there is no guaranteed frametime from frame to frame with a fluctuating framerate. However, if the framerate is limited by an FPS cap at all times (and doesn’t drop below it), there is now a constant, predicable frametime, and the pre-rendered frames queue effectively becomes “0” until the framerate drops below the cap again, at which point said queue resumes. For that reason, even if there isn’t an in-game limiter available, an RTSS limit actually has potentially lower input lag than uncapped at the same framerate within the G-SYNC range.

As for Overwatch’s “Reduced Buffering” option, that’s their equivalent of NVCP’s Maximum pre-rendered frames at “1.” However, again, you still need the -3 FPS limit on top of that to stay within the G-SYNC range. And I do recommend the Overwatch FPS limiter over RTSS for that specific game.

And yes, the RTSS limiter is only active when the framerate is at or above the set limit; whenever the framerate drops below the set limit, the RTSS limiting function is not active.

Finally, no, your VRAM size has nothing directly to do with either the over-queuing of frames or the pre-rendered frames queue. VRAM is primarily there for games to access textures and other assets, as it typically has much faster access times than system RAM or hard drives.